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This episode is brought to you by the song Like This -- Patrick Olsen’s new single. It’s available now on all streaming services.

Dr. Emmett Chappelle developed a test to find living microbes on other planets, and while it hasn't yet been used to find life amongst the stars, we've found many applications for it here on Earth

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This episode is brought to you by the song Like This,.

Patrick Olsen’s new release single. It’s available now on all streaming services. [♪ INTRO].

The search for life in the universe remains one of the most important missions in science. But if we hope to find life on other worlds, we first need a way to detect it, especially since it might be too small for scientists or robots to easily see. Researchers in all fields of science continue to explore this challenge, and one of the first to do it successfully was Dr.

Emmett Chappelle. Back in the 1960s, he developed a simple test that identifies life by making it glow like a firefly. And while they haven't found life on Mars just yet, his techniques have found a whole host of unexpected and life-saving uses right here on planet Earth.

Chappelle was born in the midst of segregation in Phoenix, Arizona in 1925. The all-Black schools he attended were denied educational resources that schools for white students had, but he worked hard and graduated at the top of his class. He was then drafted into the army, and was wounded twice while fighting in Italy during World War II.

But being in the army gave Chappelle access to engineering classes and specialist training that wouldn’t have been available in segregated schools, and there he thrived. After the war, he earned degrees in electrical engineering, biology, and biochemistry, before beginning a research career at the. Research Institute for Advanced Studies in Baltimore in 1958.

This was an exciting time for the space program, and Chappelle started out researching how to ensure the first astronauts had enough safe air to breathe. One of his ideas involved bringing live plants up with them to help avoid carbon monoxide poisoning. But before long, he became interested in how scientists might detect life on other planetary bodies, like the Moon or Mars.

And, in the mid-1960s, he went to work for NASA. His key insight was that all living things have something in common: they all use energy. And, at least on Earth, the universal currency for energy inside a living thing is a molecule called adenosine triphosphate, or ATP.

Virtually all known living things, from simple bacteria to the most complex mammals, are guaranteed to have ATP inside their cells. And, in nature, ATP is made almost exclusively by living things, so if a test can detect ATP, it could detect life. And how can we detect ATP?

For that, Chappelle had an ingenious idea. Fireflies don’t just rely on ATP to stay alive. They also use it to power their iconic glowing behinds.

In the last few sections of their abdomen, an enzyme called luciferase takes ATP and transfers some of its energy to a chemical called luciferin. Both the enzyme and the chemical share root words meaning “light bearing”. That’s because, after a couple more chemical transformations, the modified luciferin molecule ends up with one too many electrons.

This extra electron is easily lost, and when that happens, the molecule emits energy in the form of light. So Chappelle and his colleagues at NASA developed a relatively simple test, using the very same stuff that makes fireflies glow. Basically, luciferase and luciferin can be added to a crushed up sample of soil.

If there was anything living in there, then the ATP it produced would combine with the luciferin, and the sample would light up! Chappelle and his colleagues developed this test ahead of NASA’s. Viking missions to Mars in 1976, in the hope that the robotic laboratory could carry out the test and look for microscopic life in the Martian soil.

Unfortunately, although both Viking landers carried several tests for life to the surface of the Red Planet, the so-called firefly test didn’t make the cut. But it has proven super useful for detecting life here on Earth. Now, I know what you’re thinking: we know there’s life here already!

But there are some places that doctors and scientists really don’t want to find living microbes, such as in your urine, or on objects that are supposed to be sterilized. So Chappelle developed his invention even further, finding a way to relate the number of bacteria in a sample to the intensity of the light that the test produced. In this way, the fluorescent ATP test became an important tool for doctors to detect infections in our blood and urine.

And scientists have found a whole host of other uses for fluorescent tests based on firefly chemicals, including fluorescent tags that glow when a gene is active in a cell, and glowing cancer cells to help visualize tumors in mice. Chappelle went on to find other ways of making life glow, too, coming up with a way to make plants fluoresce by shining a laser on them, which is used by satellites to figure out the health of crops from space. But thanks to his visionary work with firefly light,.

Emmett Chappelle was awarded NASA’s Exceptional Scientific Achievement Medal in 1994, and inducted into the National Inventors Hall of Fame in 2007. And even though he passed away in 2019, his legacy lives on in his glowing reputation and innovations that created new ways for scientists to learn across dozens of fields. Thanks for watching this episode of SciShow Space, which was brought to you by Patrick Olsen, the musician behind the Music for Scientists album.

He has a new single out now called Like This. It’s a fun, eccentric, alternative pop song about being aware of your senses and anatomy. But it’s hard to describe just in words.

If you want to listen for yourself, click the link in the description to start streaming Like This by Patrick Olsen.